Koshi Basin ecology
Connecting flow and ecology in the Koshi Basin
Freshwater ecosystems are increasingly vulnerable to change from people and climate. Working in the Koshi Basin, Nepal, the CSIRO Sustainable Development Investment Portfolio (SDIP) team collaborated with Nepalese organisations to understand the ecological water requirements of aquatic ecosystems in order to manage water resources and protect ecosystems.
Economic development, such as hydropower and agricultural irrigation, accompanied by climate change pressures mean that future water availability in the Koshi River Basin for freshwater ecosystems is increasingly threatened.
Linking river flow and ecology
The fact sheet and report Connecting flow and ecology in Nepal: current state of knowledge for the Koshi Basin brings a focus to the relationship between river flow and ecology to increase our understanding of how future hydrological changes in the Koshi Basin (and beyond the Basin) might impact different ecological components of the ecosystem. This is valuable information to assist in Nepal’s water reform journey and fill knowledge gaps about freshwater ecosystems.
The report established a baseline understanding of the current knowledge in relation to ecological water requirements of aquatic ecosystems under natural flow variability conditions. It also stimulated research interest to address knowledge gaps and investigate potential indicator species of the ecological impacts of flow change in the future.
Conceptual models were created from expert opinion, workshops and literature reviews to highlight the known links between river flow and specific ecological components such as birds, fish, buffalo, crocodiles or gharials, invertebrates, flora and the freshwater Ganges River Dolphin.
For the first time in Nepal and the Koshi Basin, both qualitative and quantitative flow ‐ ecology relationships were collated. The quantitative data expresses specific thresholds to flow change, which once exceeded cause a change, generally a decline, in native species populations. The qualitative data refers to knowledge which comes from observation but has not been scientifically tested to determine a specific threshold to flow change.
The reporting process and collaborations also highlighted some of the knowledge gaps for understanding flow and ecology in Nepal. These include the:
- lack of floristic and faunal inventory at the basin scale
- lack of knowledge to relate connectivity between terrestrial, riparian and aquatic systems
- importance of hydrological connectivity upstream and downstream
- quantitative and qualitative relationships for all ecological components especially river birds and macroinvertebrates.
CSIRO and its SDIP ecology program in Nepal built a knowledge base on water‐ecology‐livelihood relationships necessary to conduct integrated assessment of changes in flow regimes. These activities were aligned as collaborations with other key knowledge players in the region, especially universities.
As part of this project, Nepal ecologists supervised three Nepali Masters students to undertake field work to determine flow-ecology relationships by understanding the water requirements and therefore habitat requirements of the Ganga dolphin, macroinvertebrates, birds, and aquatic vegetation. These environmental assets are thought to be some of the ecological indicator species of flow change in Nepal.
Wetlands in and around the Koshi Tappu Wildlife Reserve were selected as the study area. Field work (data collection) was undertaken seasonally with a field visit once per season. An additional PhD student was supported to investigate the links between Ganga Dolphin and flow.Find out more about this project by reading our fact sheet
Project leader: Dr Tanya Doody
This SDIP work is part of a portfolio of investments supported by the Australian Government addressing the regional challenges of water, food and energy security in South Asia.
The SDIP2 aims to improve the integrated management of water, energy and food in the Himalayan river basins, addressing climate risk and the interests of women and girls. It seeks to:
- strengthen practices for regional cooperation
- generate and use critical new knowledge to enhance regional cooperation
- improve regional enabling environment for private sector engagement.